planetarium

American  

[plan-i-tair-ee-uhm] / ˌplæn ɪˈtɛər i əm /

noun

• planetariums,
  plural
• planetaria
  plural

1. an apparatus or model representing the planetary system.

2. a device that produces a representation of the heavens by the use of a number of moving projectors.

3. the building or room in which such a device is housed.

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planetarium British  

/ ˌplænɪˈtɛərɪəm /

noun

1. an instrument for simulating the apparent motions of the sun, moon, and planets against a background of stars by projecting images of these bodies onto the inside of a domed ceiling

2. a building in which such an instrument is housed

3. a model of the solar system, sometimes mechanized to show the relative motions of the planets

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Other Word Forms

Noun Inflected Forms

• planetaria
  plural
• planetariums
  plural

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Etymology

Origin of planetarium

1765–75; < New Latin, noun use of neuter of Latin planētārius planetary; cf. -arium

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Explanation

A planetarium is a theater where you can look at images of planets, stars, and other celestial bodies on the dome-shaped ceiling. Planetariums host school field trips by day, and can even host Pink Floyd laser light rock shows by night. Use the noun planetarium for the projector that shines light onto the surface of the building's dome, recreating solar systems and constellations — and also for the building itself, where such a show is put on. Because planetarium is a Modern Latin word (from the roots planeta, or "planet," and -arium, "a place for,"), its plural can be either planetariums or planetaria.

Example Sentences

See Examples For:

planetarium planetaria planetariums

Imo Bell, a planetarium astronomer at Royal Greenwich Observatory, said: "We're not going to get one this good for a really long time."

From BBC ● Aug. 10, 2026

It added that they would create an "astronomical observatory, planetarium and visitor centre in the heart of the internationally-recognised Galloway Forest Dark Sky Park".

From BBC ● Mar. 3, 2026

That’s what happens when you have a payroll of $350 million and use it to amass more stars than the average planetarium.

From The Wall Street Journal ● Dec. 16, 2025

A 37-year-old convict, who had more than a year still to serve for theft, fled on November 14 during an outing with fellow prisoners to the city's planetarium.

From Barron's ● Nov. 28, 2025

When the show was over, my teacher had to drag me out of the planetarium.

From "Shine!" by J.J. and Chris Grabenstein

Eye of the Dream is an adaptation of this remarkable library of metadata, an audio-reactive Kaleidoscopic film for 360 domes and planetaria.

From The Verge ● Aug. 18, 2021

With habitual German thoroughness another prototype institution has been achieved, matching the German planetaria and industrial museums.

From Time Magazine Archive

"I heard about planetaria, read about them, thought it would be well for Philadelphia to have one," he explained.

From Time Magazine Archive

Youthful Germans will learn astronomy from planetaria installed in eleven cities.

From Time Magazine Archive

Interest in planetaria is, I should say, an acquired taste; but there can be no doubt as to the industry and ingenuity of this inventor.

From A Wanderer in Holland by Herbert Marshall, R.W.S.

An alternative kind of venue is offered by Cosm, which emerged after a merger involving Evans & Sutherland, a company that developed digital projection technology widely used in planetariums and science centres.

From BBC ● Mar. 30, 2026

Cosm — a name blending cosmos and colosseums — “is a nod to our history and heritage of great scientists and planetariums and engineers,” Terry says.

From Los Angeles Times ● Sep. 26, 2023

His creations, which ranged from tabletop size to more than 40 feet high, resembled a combination of planetariums, construction girders, carnival rides and pinball machines.

From Washington Post ● Jul. 31, 2021

Over the years, she’s created several works that revolve around circularity, most notably planetariums and timekeepers.

From New York Times ● Oct. 10, 2018

As such they were comparable to the orreries of the 18th century and to modern planetariums; that they also showed the time and rang it on bells was almost incidental to their main function.

From On the Origin of Clockwork, Perpetual Motion Devices, and the Compass by Derek J. de Solla (Derek John de Solla) Price

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